The study involved 418 adults from the registry of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation who received a second allogeneic HCT (allo-HCT2; n = 137) or DLI (n = 281) for post-allograft–relapsed AML (circulating myeloblasts or ≥ 5% bone marrow infiltration). Eligible patients were those who received a first allogeneic HCT in complete remission between 1992 and 2015 for de novo or secondary AML.

The primary outcome measure was 2- and 5-year survival after allo-HCT2 or DLI. Overall, 55% of patients were male and mean age was 46 years (interquartile range = 37–57 years). For the allo-HCT2 and DLI groups, remission status at the time of intervention was complete remission 2 in 34% vs 13%, complete remission 3 in 5% vs 5%, relapse 1 in 53% vs 65%, and relapse 2 in 8% vs 17%.

Survival Outcomes

Median follow-up for surviving patients was 63 months. For the allo-HCT2 group vs the DLI group, overall survival was 26% vs 25% at 2 years and 19% vs 15% at 5 years (P = .86 overall).

Overall survival was better among patients in both groups when the procedures were offered while the patient was in complete remission (hazard ratio = 0.55, P < .001). Overall survival was poorer irrespective of treatment group among patients relapsing < 6 months after first allogeneic HCT, with 5-year overall survival of 9% in the allo-HCT2 group and 4% in the DLI group (P = .86).

The investigators concluded, “Heterogeneity of the patient-, disease-, and treatment-related characteristics limit the ability to recommend one approach over another. Findings of this study highlight that best outcomes seem to be achieved in patients relapsing 6 or more months from [first allogeneic HCT] or those in complete remission at the time of either allo-HCT2 or DLI.” ■